Speedometer.



w. N. DENN'ISON.

SP EEDOMETER.

APPLICATION FILED APR- 3..l912.

Patented Aug. 31, 1915.

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WITNESSES ATTORNEY cow/mam PLANOGRAPH conwnsnmc'rou, D. c,

ill TAT WILBURN N. DENNISON, OF MERCHANTVILLE, NEW JERSEY, ASSIGNOR TOVICTOR TALKING MACHINE COMPANY, A CORPORATION OF NEW JERSEY.

SPEEDOMETER.

Specification of Letters Patent.

Patented Aug. 31, 1915.

Application filed April 3, 1912. Serial No. 688,280.

To all whom it 1. my concern Be it known that I, VVILBURN N. DENNI- soN,a citizen of the United States, and a resident of liferchantville, NewJersey, have invented certain new and useful Improvements inSpeedometers, whereof the following is a specification, reference beinghad to the accompanying drawings.

This invention particularly relates to that class of speedometerswherein relatively rotatable driving and driven fans, respectivelyhaving blades or vanes, are disposed in such opposed relation that thepositive rotation of one of said fans tends to effect the rotation ofthe other, to actuate means indicating the speed of the mechanism towhich the driven fan may be connected. Such speedometers, however, havebeen found to be inaccurate and otherwise unsatisfactory, which isbelieved to be due, among other causes, to the fact that the air currentcreated by the driving fan are permitted to diffuse, and, therefore,such air currents cannot exert their full force against the blades ofthe driven fan to deflect the latter in precise ratio to the speed ofrotation of the driving fan.

The principal objects of this invention are, to obviate the difficultiesnoted, and to substantially eliminate the inaccuracies incident thereto,by providing efiicient means arranged to confine the air to the zone ofactivity of the blades between the co-acting fan members.

Another object of this invention is, to provide 'fan members forming aclosure having cylindrical walls or flanges, disposed respectivelywithin and without the annular path of the fan blades, and totelescopically arrange said walls or flanges so as to form substantiallyair-tight seals for confining the air within the closure formed by thefan members, and yet permitting the free relative rotation, and theaxial' adjustment of said fan members, without breaking the seals.

Other objects of this'invention are, to provide mountings for the fanmembers which permit their relative axial adjustment; to provide meansto effect the relatively axial adjustment of said fan members, to varythe distance between the blades and to provide means for adjusting saidtension means to regulate the Zero position of said driven fan. j

Another object of this invention is, to provide an air-tight casinginclosing said fan members, in order to prevent communicati on betweenthe air chamber formed thereby and the atmosphere, to insure against thepossibility of the instrument being afi'ected by change of altitude andother barometic or atmospheric changes.

Further objects of this invention are, to provide a simple, efficientand accurate speedometer which may be readily mounted on, or directlyconnected with, the governor shaft or other positively driven motormember of a talking machine, and be rotated therewith to indicate thespeed of rotation of the turn-table, whereby'absolute" accuracy isattained, since lost motion between the governor and regulator may beeffectively obviated.

This invention further includes all of the various novel features ofconstruction and arrangement hereinafter more definitely specified.

In the accompanying drawings, Figure 1 is an inverted plan view of atalking'machine conveniently vembodying a speedometer constructed inaccordance with. this invention, the cabinet being shown in section forconvenience of illustration; Fig. 2"is acentral longitudinal sectionalview of the speedometer, per 86, Fig. 3 is a transverse verticalsectional view of the speedometer shown in Fig. 2, taken on the line 33in said figure; Fig. 4 is a transverse vertical sectional view taken onthe line 4i4 in Fig.

2; Fig. 5 is a fragmentary vertical sectional view taken on the line 55in Fig. 1; Fig. 6 is a fragmentary perspective view of the fan members;and Fig. 7 is a fragmentary perspective view of the fan members embody--ing a modification of the blades.

In said figures,the cabinet comprises the walls 8 and the lid or cover9, to which the frame 10 of the motor mechanism is secured. Said motormechanism comprises the spring barrels 11 having the winding stem 12,and is connected through suitable gearing with the governor 14, whichcomprises the rotatable shaft or spindle 15, and the disk 16 axiallymovable on said spindle 15 by the centrifugal movement'of the governorballs 17.- The axial movement of said disk 16 in the direction of thearrow indicated thereon, and, consequently,the speed of rotation of thegovernor, are limited by the adjustable friction pad 18, carried on thearm 19 secured to the rockshaft 20, which is journaled in suitablebearings 21 and 22 in the frame 10, and which has its free end bentlaterally to form a lever 23. Said lever 23 may be adjusted verticallyto shift the pad 18 into different positions to vary termined speed ofrotation of said governor, by the set screw 25 extending through the lidor cover 9 and having its head 26 projecting exterior thereto forconvenient actuation by the operator.

The spindle 15 has an extension 27 rotatable therewith, and having acoupling-head 28 provided with pins 29 conveniently engaged in suitableapertures or recesses 30 in the opposed coupling-head 31, which issecured to the shaft 32 of the speedometer. The talking machinemechanism herein shown and described is typical, it being understoodthat the speedometer may be otherwise connected to said mechanism, ormay be connected with mechanism otherwise constructed.

The speedometer is provided with a casing 33 having a front cover 34 anda protecting cap 35, the casing 33 having its outer periphery recessed,and the cover 3 1 having a flange 36 fitted to said recess and securedthereto by screws 37, with its outer cylindrical face flush with theouter cylindrical face of the casing 33, and the protecting cap beingsecured to the front face of said cover 34 by screws 39, and inclosingadjustable mechanism, hereinafter described, in a substantiallyair-tight chamber.

The shaft 32 is mounted for rotation in the adjustablebearing block 40,which is in threaded engagement with a reduced cylindrical extension 41of the casing 33, and is provided with suitable apertures 42 for theconvenient engagement of a spanner-wrench, whereby said bearing blockmay be adjusted axially with respect to the casing 33.

The shaft 32 has a reduced end trunnion the prede- I fan blades or vanes63 preferably H, which is conveniently journaled within the casing 33 ina bearing ewel 15, having a suitable mounting 16 which is convenientlyretained in the bearing support a7 by the an nular nut 48, which is inthreaded engagement with said bearing support 17. The bearing support 47carries a sealing member 19, preferably having the substantiallycylindrical extension embracing the jewel bearing members, and is itselfcarried by the spider frame 50, having a cylindrical wall 51 whichextends away from said sealing member -19. Said spider frame 50 is alsoprovided with a peripheral cylindrical wall or rim having a radiallyextending peripheral flange secured to the inner wall of the casing 33by the screws 5 1; the cylindrical wall 51 and the peripheralcylindrical rim 52 of said spider frame being preferably joined by thearms 56, as may be best seen in Fig. 4: of the drawings.

The shaft 32 carries the driving fan, comprising the hub 58 of therotatable fan disk or wall 59, which is provided with the cylin dricalrecess the cylindrical wall 60 of which embraces the cylindrical sealingmember 19 and coiiperates therewith to form a substantially air-tightjoint, and said fan disk 59 is also provided with the peripheralcylindrical wall, rim or flange 61 comprising a sealing member,extending in close concentric relation with the peripheral cylindricalrim of the stationary spider frame 50, and forming therewith asubstantiallv air-tight joint. Said fan disk 59 carries an annularseries of disposed radially in equally spaced relation within thecylindrical wall 61 of the disk 59.

As best shown in Fig. 2 of the drawings, the vanes 63 are provided withlugs 6-1 and 65, respectively extended through suitable apertures 66 inthe fan disk 59 and riveted over, preferably by respectively bendingsaid lugs 64 and 65 in opposite directions, whereby said vanes aremaintained in co-axial. radial. planes, with their outer edges inabutted relation with the peripheral rim 61, and their inner edgesextending into close proximity to the cylindrical wall 51,

A ball thrust bearing is preferably provided between the hub 58 of thedriving fan and the bearing block -10, and comprises the spacing ringGl'for the balls 68. The shaft 32'is provided exterior to the casing 33with a collar 69 suitably engagedwith said shaft by the set screw 70,and having a bearing rim 71 engaging the outer face of said block 40 tomaintain said thrust, bearing in its operative position.

The driven fan comprises the rotatable fan disk 72, carrying the fanblades or vanes 73 and having a flanged cylindrical outer wall or rim Tl forming a sealing member, telescopically embracing the cylindricalwall of the spider frame 50 and the cylindrical rim 61 of the drivingfan, to form a substantially air-tight joint, and having the centralrecess the cylindrical walls 75 of which inclose the hub 76 and areconveniently secured thereto. Said hub 76 also carries the cylindricalsealing member 78, having its free cvlindrical Wall telescoped with thecylin'drical wall 51 of the spider frame 50, thereby coiiperating withthe said cylindrical wall 51to form a substantially air-tight joint, andembracing the adjacent end of the bearing support 47.

The hub 76 is carried by the spindle 79, which is provided with reducedopposite end trunnions 80 and 81, the trunnion 80 being supported in thejewel bearing 82 having the mounting 83, with its end disposed againstthe thrust jewel bearing 84 having the mounting 85 and the trunnion 81being supported in the jewel bearing 90 having the mounting 91, with itsend disposed against the thrust jewel bearing 92 having the mounting 93.

The bearing mountings 83 and 85 are secured in the bearing support 47 bythe annular nut 87, and the bearing mountings 91 and 93 are secured bythe annular nut 94 in the adjustable bearing stud 95, which is inthreaded engagement with the wall of the cover 34, and which isprevented from accidental displacement by the jam-nut 97.

The fan disk 72 carries the annular series of blades or vanes 73 inopposed relation to the blades or vanes 63, and said blades or vanes 73are secured to said fan disk 72 by lugs 101 and 102 respectivelyextending through suitable apertures in said fan disk 72 and rivetedover, preferably by bending said respective lugs in opposite directions,as shown in Fig. 4, and said blades or vanes have their outer endsabutted against the flanged rim 74, and their inner ends terminatingshort of the cylindrical wall of the recess 75.

In the preferred form of this invention, the blades 73 extend outwardlyfrom the plane wall of thefan disk 72 for a short distance, normalthereto, and have a portion 77 turned obliquely and extended rear-\vardly with respect to the direction of rotation of the fan whenactuated by the driving fan, as best shown in Figs. 2, 4 and 6.

In the modification shown in Fig. 7, however, the blades 103 of thedriven fan are flat, like the blades 63 of the driving fan, and althoughthe blades have been shown and described as being in co-axial radialplanes, it is to be understoodthat they may be otherwise disposed, as,for instance, in planes tangent to a common circle.

The spindle 79 carries the collar 105, which is secured to the inner endof the helical hairspring 106, the outer end of which is secured to thepost 107, which may be adjusted circularly around the axis of saidspindle 79, in the opening 108 in the wall of the cover 34, and which iscarried by the plate 109 embracing the bearing stud 95 and havingcircularly disposed slots 110, through which the set screws 111 extendin threaded engagement with the cover 34.

It will be observed that the tension of the hairspring 106 may be variedby rotatively adjusting the plate 109 so as to regulate the zeroposition of the driven fan comprising the fan disk 72 and the blades orvanes 73. The rotative movement of said driven fan may be limited by theengagement of the projecting post 112, which is carried thereby, withthe stopping bar 113, which extends, at its lower portion, along theinner face of the cover 34 and is secured thereto by the screw 114, andwhich has the offset upper portion extending through the aperture 115 inthe post 116 projecting from'the cover 34 and arranged to maintain thefree offset end of said stopping bar 113 in the path of said post 112.

The rim 74 of the fan disk 72 conveniently provides means forcarrying'suitable graduations, or other characters, indicating the speedof rotation of the shaft 32, and may preferably carry a strip 118 ofpaper, metal, celluloid, or other suitable material, having suchgraduations or characters indicated thereon and arranged to be presentedinto registry with the sight aperture 119 in the cylindrical wall 120 ofthe casing 33, said sight aperture 119 being preferably covered by'theglass or other transparent plate 121 secured thereto by the flangedframe or rim 122.

As best shown in Fig. 5, the lid 9 of the cabinet is provided with anaperture 125 suitably disposed in registry with the sight aperture 119,and said aperture 125 may be preferably provided with the escutcheonplate 126 having its central portion 127 depressed toward said sightaperture 119, and provided with a suitable aperture 128, through whichthe speed indications onthe strip 118 carried by the rim 74 of the fanmember 72 may be read.

To insure a substantially air-tight closure formed by the casing 33,cover 34 and cap 35, the bearing block 40 may be provided with a pocket130, having extensions 131 and 132 embracing the shaft 32, andsubstantially forming a stufling-box which may be packed with grease135.

From the foregoing description, it will be readily observed that thetelescopically disposed walls 61 and 74 at the periphery of the fandisks, and the cylindrical walls of the sealing members 49 and 78, andthe cylindrical walls 60 and 51 respectively, at the center of thedisk59 and spider 50, coiiperate to form substantially air-tight sealsbetween the fan members, and provide anannular substantially air-tightchamber, within which the air is confined in the zone of activity of theblades, whereby a greater accuracy is attained in the actuation of thedriven fan by the driving fan, than is attained by speed indicatorswherein the air is unconfined, and is free to diffuse. Furthermore, itwill be noted that as the fans are adjusted toward each other toincrease the pressure of the air created by the driving fan and directedupon the driven fan, the overlap of the members forming the airsealswill be similarly increased.

As has been heretofore described and fully set forth, a substantiallyairtight seal is provided between the sealing member 49 and thecylindrical wall of the recess 16; between the sealing member 78 and thecylindrical wall of the recess 50; between the flanged rim 7a and theouter cylindrical wall 52 of the spider frame 50; and between thecylindrical rim 61 and the inner cylindrical surface of the wall or rim52. In the drawings the space between these various telescoping flangesis shown on an exaggerated scale for the sake of clearness' inillustration.

Although the fans are shown as having members disposed in telescopicrelation to form seals which do not interfere with the free relativerotation of said fans, it is to be understood that air-seals may beformed between said fans by having members in abutted relation, or otherstructures may be employed to confine the air in the zone of ac tivityof the blades, and, therefore, it is not desired to limit this inventionto the precise details of construction and arrangement herein set forth,as various modifications may be made therein without departing from theessential features of the invention as defined in the appended claims.

Having thus described my invention, I claim:

1. A speedometer comprising opposed relatively rotatable coaxial aircompressing members, and means extended therebetween for confining theair substantially within the zone of activity of said members.

2. A speedometer comprising coaXially mounted driving and driven fans,and coacting sealing members carried by and extending between the fansto confine the air.

8. A speedometer comprising co-acting relatively rotatable fan disks,and blades on adjacent faces of the disks, and means disposedperipherally on one of the disks and extending toward the other disk,for confining the air.

A. Relatively rotative members forming a substantially air-tight chamberand respectively having means in said chamber, cooperative when one ofsaid members is positively actuated, to shift the other member intoposition to indicate the speedof rotation of said'actuated member.

5. A speedometer comprising relatively rotatable members, cooperative toform an inclosed substantially air-tight chamber, and respectivelyhaving members within said chamber, cooperative when one of said membersis positively rotated to affect the actuation of the other member intoposition to indicate the speed of rotation of said positively rotatedmember.

G. A speedometer comprising relatively rotatable members disposed intelescoped relation, and forming a substantially air-tight chamber, andrespectively carrying opposed vanes disposed in such relation that whenone of said members is rotated, the other member is actuated by the aircurrents generated by said rotated member to indicate the speed ofrotation of the rotating member.

7. A speedometer comprising opposed fan members having peripheralflanges in telescopic relation, and forming an inclosed substantiallyair-tight chamber, vanes carried by the respective fan members anddisposed in opposed relation, one of said members being turned by theair currents generated by the rotation of the other member, andindicating its speed of rotation.

S. A speedometer comprising relatively rotatable members having sealingmeans disposed in telescopic relation, and forming an inclosedsubstantially air tight chamber, blades or vanes carried by therespective members within said chamber, one of said members beingprovided with speed indicating characters, turned by the motion of theair confinedin said chamber, effected by the rotation of the othermember.

9. A speedometer comprising opposed relatively rotatable fan membershaving telescopically disposed peripheral sealing members forming asubstantially air-tight chamber, and respectively carrying opposedblades or vanes cooperative when one of said members is rotated toeffect a motion of the air confined therein, to actuate the othermember, means tending to retard the movement of said actuated member,and means carried by said actuated member to indicate the speed of therotating member.

10. A speedometer comprising relatively rotatable fan members havingsealing members telescopically disposed, and forming a substantiallyair-tight chamber, and blades or "anes carried by the respective fan members in opposed relation, within said chamber.

11. A speedometer comprising relatively rotatable fan disks havingperipheral sealing members disposed in telescopic relation, and forminga substantially air-tight chamber, means connected to positively rotateone of said disks, resilient means operative to retard the rotation ofthe other disk, means carried by said respective disks within saidsubstantially air-tight chamber, and operative when the positivelyrotated disk is actuated to produce air currents operative to turn theother disk in opposition to said retarding means.

12. In a speedometer, the combination with a casing, of relativelymovable fan members disposed within said casing, and having peripheralwalls in telescopic rela tion, arranged to form a substantially airtightchamber, blades or vanes carried by the respective fan members inopposed relation within said chamber, means journaled in said casing,and connected to rotate one of said fan members, to produce a turningmoment for actuating the'other fan member, and means operative to retardthe movement of said actuated fan member.

13. A speedometer comprising relatively rotatable opposed fan membersforming a substantially air-tight chamber and having blades, some ofwhich are bent obliquely with respect to the side walls of said fanmembers.

14. A speedometer comprising relatively rotatable fan membersrespectively having blades disposed in coacting relation, and havingsealing members arranged to form an annular substantially air-tightchamber, for confining air in the zone of activity of said blades.

15. A speedometer comprising relatively rotatable opposed memberstelescopically arranged, and forming anair seal, blades carried by saidmembers and disposedin coacting annular series within said air seal, andsealing means disposed within said annular series of blades and formingair seals with said members, for confining the air in the annular zoneof activity of the blades.

16. A speedometer comprising opposed fan members forming an inclosedchamber, one being positively connected with the governor shaft oftalking machine motor mecha nism, and the other being rotated by therotation of the first mentioned fan member.

17 In a speedometer, the combination with a casing, of adjustablebearings in said casing, relatively rotatable fans having blades orvanes in opposed relation supported in said bearings, means topositively rotate one of said fans to drag the other fan aroundtherewith by air currents thus pro duced, and means to adjust saidbearings to vary the drag effected by one fan upon the other fan.

18. In a speedometer, the combination with a support, of adjustablebearings carried thereby, an intermediate bearing disposed between saidadjustable bearings, a spider frame secured to said support and carryingsaid intermediate bearing, relatively rotative fans, a shaft for one ofsaid fans, movable axially with its adjustable bearing, and a spindlefor the :other fan,

position by and forming air seals with said fan memhers, the inner andouter air seals being operative to confine air within said fan membersin the annular zone of activity of the blades.

20. In a speedometer, the combination with a casing, of relativelyrotative fan members having peripheral flanges in telescopic relation,operative to form a substantially air-tight chamber, blades or vanesrespectively carried by the fan members in opposed relation, a spiderframe secured to said casing, and extending into said chamber betweensaid blades or vanes, and having a bearing supporting said fan members,within said chamber.

21. In a speedometer, the combination with a casing having bearings, ofrelatively rotatable fan members having telescoped peripheral wallsforming a substantially air-tight chamber, blades or vanes respectivelycarried within said fan members, in opposed relation, a spider framecarried by said casing, and having a cylindrical rim disposed betweensaid telescoped walls, and having connecting arms disposed between saidblades or vanes and supporting bearings within said chamber, and shaftsor spindles respectively journaled in said bearings to support said fanmembers.

22. In a speedometer, the combination with a casing having bearings, ofrelatively rotative fan members having peripheral walls-in telescopicrelation, forming a substantially air-tight-chamber between said fanmembers, a spider frame secured to said casing, and having a cylindricalrim extending between said telescoped walls, and arms extending betweensaid fan members, a bearing supported within said chamber by said spiderframe, shafts or spindles journaled in said bearing and respectivelysupporting said fan members, means carried by the respective fan memberswithin said chamber, and cooperative when one of said fan members isrotated to effect the turning of the other fan member, means tending toretard the movement of the last mentioned fan member, and meansoperative to limit its movement.

23.In a speedometer, the combination with a support, of relativelyrotative fan members, having peripheral flanges dis- .bers, meansconnected to positively rotate one of said members, and means tending 1,to retard the rotation of the other member,

the flange of the retarded member being provided with speed indicationsto designate the speed of rotation of said positively rotated member.

24. In a speedometer, the combination with a support having bearings, ofrelatively rotative members having telescopically disposed rims forminga substantially air-tight chamber between said members,

blades or vanes respectively carried by said members in opposed relationand cooperative when one member is rotated to tend to drag the othermember in the same direc tion, a spider frame carried by said supportand extending between said fan members, a bearing carried by said spiderframe and disposed within said chamber, means journaled in said bearing,rotatably supporting said fan members, and means arranged to axiallyadjust said fan members to vary the effective drag between the vanes ofsaid fan members.

25. In a speedometer, the combination with a casing, of relativelyrotatable fan members having sealing means forming a substantiallyair-tight chamber between said fan members, adjustable bearings carriedby said casing, blades or vanes respectively carried by said fan memberswithin said casing in opposed relation, a spider frame carried by saidcasing and extending between said members, and having arms extendingbetween said vanes, a bearing member carried by said spider frame withinsaid chamber, and provided with separate bearings,,means operative topositively rotate one of said members to affect the actuation of theother member, and means arranged to axially adjust said members to varythe effect of one member upon the other member.

26. In a speedometer, the combination with a casing having a sightaperture, of relatively rotatable fans disposed within said casing, andhaving peripheral flanges forming a substantially air-tight chamberbetween said fans, means connected to positively rotate one of said fansto actuate the other fan by currents of confined air, means tending toretard the movement of the actuated fan, and means carried by the flange1 of said actuated fan and having indications arranged to register withsaid sight opening in accordance with the speed of rotation of saidpositively rotated fan.

27. In a speedometer, the combination with a casing having a sightaperture, of relatively rotative hollow fan members having peripheralflanges in telescopic relation, forming a substantially air-tightchamber, blades or vanes respectively carried by said fan members withinsaid chamber in opposed relation, means separately supporting said fanmembers, means connected to positively rotate one of said fan members toeffect the actuation of the other fan member by confined air currents,resilient means tending to retard said actuated fan member, and meanscarried by the flange of said actuated fan member, and having speedindications registerable with said sight opening to indicate the speedof rotation of the positively driven fan member.

28. In a speedometer, the combination with a support having bearings, ofa fan member having a central outward recess forming a cylindrical wall,and a peripheral cylindrical flange, a spider frame carried by saidsupport and having a cylindrical rim surrounding said flange intelescoped relation, and having a central recess forming a cylindricalwall, a bearing member supported in the recess of said spider frame, andcarrying separate bearings, a cup carried by said spider frame, having acylindrical flange in telescopic relation with the cylindrical wall ofthe central recess of said fan member, a second fan member having aperipheral flange in telescopic relation with said spider frame andflange of said first mentioned fan member, and having an inwardlydisposed central recess, providing a cylindrical wall, and a cup carriedby said second mentioned fan member and providing a peripheralcylindrical flange in tel scopic relation with the cylindrical wall ofthe central recess of said spider frame, blades respectively carried bysaid fan members within the annular substantially air-tight chamberformed by said fan members and spider frame, and means arranged toaxially adjust said fan members to vary the effect of the vanes of onefan upon the vanes of the other, said adjustment being made withoutaffecting the air-tight joint between said fan members.

29. In a speedometer, the combination with a casing forming asubstantially airtight chamber, of relatively rotatable fan membersforming a closed chamber mounted in said casing, a shaft for one of saidmembers extending through said casing, and a bearing for said shafthaving a pocket embracing said shaft for containing grease.

30. In a speedometer, the combination with a substantially air-tightcasing, of rotively rotatable fans forming an inner closed chamber andhaving blades or vanes in opposed relation in said chamber, a shaft forone of said fans extending through said casing, and a bearing having apocket forming a stufiing-box embracing said shaft, for containinggrease or a suitable packing matei ial.

32. A speedometer comprising opposed relatively rotatableair-compressing members, means extending therebetween for confining theair substantially within the zone of activity of said members, bearingsrotatably supporting said air-compressing members, and means to adjustsaid bearings to vary the drag elfected by one fan upon the other fan.

83. A speedometer comprising driving and driven fans, coacting sealingmembers carried by and extending between the fans to confine the air,bearings rotatably supporting said fans, and means to adjust saidbearings to vary the volume of air thus confined.

34. A speedometer including relatively rotatable members, coactingblades carried by said members respectively, a casing inclosing saidmembers and blades, and means independent of said casing for confiningair between said members.

85. A speedometer comprising relatively rotatable fan walls, blades onthe adjacent faces of said walls, a casing for inclosing said walls andblades and means independent of said casing and co-acting with saidwalls for confining air in the zone of activity of the blades.

86. A speedometer comprising relatively rotatable fan walls forming asubstantially airtight chamber, and respectively having air-resistingmeans within said chamber movable with said walls.

37. A speedometer comprising relatively rotatable fan walls, forming asubstantially air-tight chamber, and having opposed blades projectingfrom said walls within said chamber.

38. In a speedometer the combination of two axially alined rotatablemembers, coacting blades or vanes carried by each of said members, meansfor adjusting one of said members axially with respect to the othenofsaid members to vary the drag eflected by one member upon the other, andsealing means movable with said members and operable in differentaxially adjust-ed positions to confine the air between said members.

39. In a speedometer the combination of two axially alined rotatablemembers, coacting blades or vanes carried by each of said members, meansfor adjusting one of said members axially with respect to the other ofsaid members to vary the drag effected by one member upon the other, andsealing means movable with said adjustable member toward and away fromthe other of said members and operable in its different adjustedpositions to confine the air between said members to the Zone ofactivity of said blades or vanes.

40. A speedometer including telescoped members separately rotatableabout a common axis, blades carried by the respective members andinterposed therebetween, and means for adjusting one of said members inthe direction of said axis.

In witness whereof, I have hereunto set my hand this 2nd day of April,A. D., 1912.

IVILBURN N. DENNISON.

Witnesses:

FRANK B. MIDDLETON, J r., JOHN D. Mynns.

Copies of this patent may be obtained for five cents each, by addressingthe Commissioner of Patents, Washington, I). G.

It is hereby certified that in Letters Patent No. 1,152,010, grantedAugust 31, 1915, upon the application of Wilburn N. Dennison, ofMerchztntville, New Jersey, for an improvement in Speodometers, an errorappears in the printed specification requiring correction as follows:Page 1, line 21, for the word current reed currents; and that the saidLetters Patent should be read with this correction therein that the samemay conform to the record of the case in the Patent Office.

Signed and sealed this 28th day of September, A. D., 1915.

J. T. NEWTON,

Acting Commissioner of Patents.

[SEAL]

